Dash or Underscore in URLs?
The question is: within the URL of a webpage should you use a dash (-) or an underscore(_) to separate words? For example: www.somesite.com/page-about-bagels.html VERSUS www.somesite.com/page_about_bagels.html
Like the Hi Definition format wars, we have an undisputed winner in the to dash or to underscore question. There is no reason to use an underscore unless a searcher will likely utilize the underscore in the search. For example, if they were tech heads they might be inclined to search for a bit of code like ‘end_of_file’ for you C junkies out there. Google will pick that phrase as a single keyword rather than 3 separate keywords in a phrase.
Google will take word1-word2 and read it as word1 and word2 as long as you utilize the dash. It does not do the same for underscore, so word1_word2 does not read to the algorithm as word1 and word2 but simply word1_word2.
Using our example above a search for ‘page about bagels’ would, all other factors being equal, result in the url somesite.com/page-about-bagels.html ranking higher than the somesite.com/page_about_bagels.html simply because Google is reading the keywords in the former and not the latter.
SO unless you have a specific reason to believe your searcher will search using an underscore as in the ‘end_of_file’ example, stick to the dash.